Telephone receiver



J. S. TIMMONS.

TELEPHONE RECEIVER. APPL'ICATiON FILED 1uLY17. 1918.

14,414, 105. Patented Apr. 25, .1922.

2 SHEETS-SHEET I.

3 vwewfoz M anon 121 a @Md 1.3. THVIMONS.

TELEPHONE RECElVER.

APPLICATXON FIL'EDJULYI7,1918.

Patented Apr. 25, 1922.

2 SHEETSSHEET 2 JOHN S. TIMMONS, OF NEW YORK, N. Y.,

ASSIGNOR, BY MESNE ASSIGNMENTS, 110

INTERNATIONAL CALLOPHONE CORIPORATION, A CORPORATION OF DELAWARETELEPHONE RECEIVER.

Application filed July 17,

To (all whom it may concern.

Be it known that 1, JOHN TiMMoNs, a citizen of the United States, and aresident of New York city, county and State of New York, have inventedcertain new and useful Improvements in Telephone Receivers, set forth inthe following specification.

This invention relates to electro-magnetic sound functioning mechanism,particularly of the type reproducing sound in response to a soundcontrolled electric variation, although including the type in whichsound is employed to produce a corresponding electric. variation throughthe variation of a magnetic circuit. More particularly, the inventionrelates to the species of this general apparatus commonly known as atelephone receiver.

The object of the invention is to improve the faithfulness of thevariation with relation to the essentials of articulate speech,particularly the faithful reproduction of articulate sound, but likewisethe creation of an electric variation in response to articulate sound.More particularly the object of the invention is to improve the soundfunctioning vibration of a diaphragm of electromagnetic material inmechanism of the above gei'ieral type. To this end an improvement in theform and construction of the permanent magnet of such a mechanism iscontemplated. A novel and improved disposition of the permanent magneticfield with relation to the diaphragm is also contemplated and afunctioning objective feature is an inertia-less loading of a soundfunctioning diaphragm to prevent false vibrations or vibrations of acharacter tending to interfere with the faithful rcproduction of theessentials of articulate speech.

,I urthcr objects'of the invention are to improve in general thestructural parts and structural arrangement of a mechanism of the abovegeneral character. the general fea tures of this latter object beingsimplicity,

ruggedness and compactness.

The above and further objects of the invention will be clear from theillustrative embodiment to which the claims are directed merely forpurposes of illustration and which is described in the following speciSpecification of Letters Patent.

Patented Apr. 25, 1922.

1918. Serial No. 245,386.

lication in connection with the accompanying drawings, which form a parthereof. and in which like characters designate corresponding parts inthe several figures.

In the drawings, Fig. 1 is a horizontal section through an illustrativeembodiment of the mechanism;

Fig. 2 is a section through line IIIZ Fig. 1, looking in the directionof the arrows;

Fig. 3 is a diagram of the magnetic circult;

Fig. at is a side elevation of the mechanism with the casing open;

Fig. 5 is a diagram drawn to a reduced scale showing the magnetic linesof force on the outer face of the diaphragm;

Fig. 6 is a similar diagram of magnetic lines of force with thediaphragm removed; and

Fig. 7 is a similar diagram showing the magnetic lines of force with thediaphragm removed of a telephone receiver of the ordinary commercialtype.

In the illustrative embodiment the hollow casing A of nonmagneticmaterial, preferably bronze, comprises a cover portion 1. and a baseportion 2 mutually provided with threads 3 by which the two parts, 1 and2, may be clamped together. The cover portion 1 is shown providing thecylindrical rim 1- of the casing as an integral. part thereof, althoughof course it is not deemed essential that this be a part of the coverpor tion instead of a part of the base portion. The cover portionprovides a circular seat 5 for the (:liaphragm G of electro-magneticmaterial, which seat surrounds the countersunk resonating space 7,leading into the sound. opening 8, preferably :l'ormed in a nipple 9having threads 10 to engage in any suitably perforated and threadedsupport ll, which may be a part of a horn mechanism, or mounting blockor mouth-piece, but which forms no detail part of the present invention.It is preferred that the diaphragm seat 5 be provided with a packingring or circular gasket 12 of suitable material such as fiber, hardrubber or the like, capable of making a hermetica-l closure when clampedagainst the rim of the diaphragm 6.

The base portion 2 of the casing A provided with perforations 13 and 14to seat the insulating bushings 15 providing a mounting for the bindingposts 17 and 18. The base portion 2 likewise preferably formed with apair of diametrically spaced sockets 19 and 20 to accommodate a spannerto facilitate the assembling of the apparatus.

A ring shaped permanent magnet B is. formed preferably as an endlessring having diametrically arrangedpolarity, as indicated in the diagramsof Figs. 3, 5 and 6, so that its north and south poles N and S are ondiametrically opposite sides of a central. zone indicated by the line Cof neutral polarity. Functionally it is understood that the ring l3 neednot be endless, although such form is preferable for structural reasons.

A pair of soft iron cores D, preferably L-shaped' and comprising thecores 22 and 23, are connected so that the outer ends of the legs 24:and 25 are suitably intimately connected, preferably by welding, to thepermanent magnet B at its rim at the locality respectively of the northand south poles. These legs 2i and 25 extend inwardly radially andcontinue integrally into the axially extendin legs 26 and 27; whichterminate in pole faces 28 and 29 approximating"the plane of thediaphragm seat 80; formed. by the outer forward rim ofthe ring shapedpermanent magnet B, which is preferably faced with a gasket 31, like thegasket 12. The edge of the magnet Bis also preferably provided with abevel 82'back of the diaphragm 6. The legs 26 and 27 of the cores 22 and28 provide a convenient mounting for the electrical controlling bobbins84: and 35, which provide the controlling winding for the instrument,the terminals 36 and 37 of which are suitably connected as by means ofsoldering with the binding posts 17 and 1.8.

The base portion 2 of the casing" A is preferablyv providedwithacountersunk channel 38 to accommodate the legs 24 and 25 which looselyseat therein. The entire magnet structure may be held assembled to thebase portion 2 in a convenient manner permitting self-seating of thediaphragm seat by means of a pair of screws 40 and if screwing into thebase portion and passing loosely through perforations 41-2 and 43 in thelegs 241: and 25. This loose connection serves to protect the terminals36 and 37 against damage when the casing A is open. in completing the asemblage of the apparatus the cover portion is screwed home on the baseportion 2, whereupon the diaphragm is uniformly clamped betweenthe seatformed on the permanent magnet B and the seat formed on the coverportion 41,. gaskets forming at hermetical closure between the interiorof the casing A and'the sound ductS. v

It is preferred thata pair of set screws 4: 1-

and a5 pierce the base portion 2'to engage" the elbows of the L-shapedcores 22 and 23 so that after the casing A is screwed together, a nicetyof adjustment of the pole faces 28 and 29 relatively to the diaphragm 6may be effected by slightly bending the resilient cores 22. and by anadjustment of the set screws ll and 4:5. .It is to be understood,however that this adjustment is not an essential feature of theinvention.

It is to be noted that the diaphragm is seated upon a circular ringitself forming the permanent magnet of the eloctro-magnetic soundfunctioning mechanism. With the polarity of this permanent magnet dualand diametrically distributed, it has been found that the magnetic linesof force distribute themselyes when the diaphragm 6 is in place,substantially as indicated in Fig. 5; There is a dense central zonebetween the localities of the pole faces 28 and29 and a second zone 51symmetrical about the neutral line C approximately bounded by concavearcs 52' and 53, which second zone is dense but not so. dense as that 50directly between the poles. lVith the diaphragm 6 removed the,distribution of the magnetic field has been found to be as thatindicatedin Fig. 6. The denser zone 50 corresponding to the zone 50 now embracesthe hold area of the pole faces 28 and 29, while the zone 51 is ofgreater extent. being bounded by smaller arcs 52 and 58. The zone of.magnetic force 51 or 51- is substantially. constant and, involving as itdoes alarge extent of the area of'tlie diaphragm o,.serves as a magneticload or inertialess load upon the diaphragm which increases in extent asits distance from the center of the diaphragm increases. This magneticheld remains substantially constant during the operation of themechanism,

the magnetic varyingef ect due to the elec- V tric circuit through thecoils Set and 35 being for the most part localized between the polefaces 28 and 29 of the cores 22 and 23, so that this effect is localizedupon the central portion of the diaphragm as designated particularly inFig. 5 by the denser area 50 of the magnetic field. In the diagram ofFig. 3 the magnetic circuit is also indicated the major circuit throughmagnetically conducting material. being straight across from the northpole N to the south pole S through the 2 cores 22 and 23, which beingbrought forward by their axially extending leg 7' 2?, causes the fieldto extend through the central portion of the diaphragm. The remainder ofthe hold. through conducting material between the poles N and this theparallel field indicated by 5i and 51 in Figs. 5 and 6. The return path.of course. is the leahage path through the air. The unique character ofthis field through the dia phragm is best un stood by comparison to thefield 60 indicated in the diagram of '5 between the pole faces 61 and 62of a telephone receiver of ordinary construction, in which the permanentmagnet is so far separated from the plane of the diaphragm thatpractically the entire magnetic field involving the diaphragm is thatimmediately springing from the pole faces themselves. The diagram ofFig. 7 has been plotted with the receiver diaphragm removed andsubstituted by a sheet of nonmagnetic material, as was the case also inthe making of the dia gram of Fig. 6, iron filings in all cases beingemployed as the visible indication of the field.

Although it is not generz'rl to employ a mechanism of the type describedfor purposes of transmitting speech, it is to be understood that thismechanism is capable of such operation. Furthermore, it is to beunderstood that the preferred embodiment illustrated has been set forthmerely for purposes of illustrating the invention. All modificationswithin the scope of the accompanying claims are contemplated.

lVhat is claimed and what is desired to be secured by United StatesLetters Patent is:

1. An electro-magnetic sound functioning mechanism comprising, aring-shaped permanent magnet providing a diaphragm-seat about one edgeand having diametrically opposed poles; a pair of cores extendingradially and axially of said magnet and fixed to said magnet atdiametrically opposite positions and presenting pole faces inapproximately the plane of its said diaphragm-seat and a diaphragm ofmagnetic material seated on said seat with its central portion under thecontrol of the field between said core pole faces while the otherportions of said diaphragm are subjected to the inertialess load of ashunt magnetic field of substantially constant strength.

2. An electro-magnetic sound functioning mechanism comprising, a closedring-shaped permanent magnet having a diaphragmseat about one edge andhaving its magnetic poles located in diametrically opposite positions inthe body of said ring, in combination with a diaphragm of magneticmaterial upon said diaphragm seat.

3. In an electro-magnetic sound function ing mechanism, a diaphragm ofmagnetic material in combination with a pair of per manent magnet-polesin magnetic connection with said diaphragm at diametrically oppositelocalities; a pair of cores magnetically connected with said permanentmagnetpoles and having pole faces radially inwardly positioned againstsaid diaphragm; and coils on said cores.

4. In sound functioning mechanism a vibratory diaphragm of magneticmaterial; means for producing a dense permanentmagnetic field throughoutan extensive area of said diaphragm including centrally lo- "and polesof cated cores of opposite polarity having pole faces localizing arelatively denser portion of said field centrally of said diaphragmalternate polarity spaced about the periphery of said diaphragm; and anelectrically controllable winding for said cores in electro-magneticcooperation with said relatively denser portion of said field while theremainder of said field. is maintained substantially constant to act asan in ertialess load upon said diaphragm.

5. A telephone receiver comprising a hollow casing having a base-portionand a cover-portion, both of non-magnetic material and having a clampingdiaphragm-seat on said cover-portion; a permanent magnet and corestructure having a diaphragm-seat; and means loosely attaching saidpermanent magnet and core structure to said base-portion, so that whensaid casing is closed together said diaphragm-seats will selfregisteruniformly and so that said permanent magnet and core structure is maintained in assemblement relatively to said base-portion when said casingis open.

6. In a telephone receiver, a clamping twopart casing; a permanentmagnet; a core secured to said permanent magnet at one end and beingbent so that its other end forms a diaphragm cooperating pole face; adiaphragm clamped by said casing opposite to said pole face; meansoperable outside of and reacting against said casing and engaging saidcore to bend the same against its inherent resiliency for the purpose ofeffecting an adjustment in the position of said pole face relatively tosaid diaphragm and a loose connection for holding said core to one partof said casing to maintain the operative re lation between said core andsaid means operable outside of said casing for effecting an adjustmentin the position of said pole-face.

7. In a telephone receiver, a casing having a base member; a curvedpermanent magnet; soft iron cores secured to said permanent magnet;windings on each said core; electric connections extending from saidwindings through said base member; a loose mechanical connection betweenone or both of said cores and said base member comprising a screwengaging said base member and pass ing loosely through said core,whereby the parts are retained in essemblage while a limited movementbetween said permanent magnet with its attached cores and said basemember is permitted.

8. In a telephone receiver, a ringshaped permanent magnet; L-shaped softiron cores secured to said magnet at diametrically opposite positionsand extending first radially inwardly and then axially at right anglesto form diaphragm cooperating pole faces; a casing of non-magneticmaterial for enclosing the magnet structure; a pair of screws passingthrough said casing to on gage respectively the radially inward portionsof said cores whereby an adjustment of the same may be effected throughtheme dium of their resiliency from outside of said casing; and a looseconnection between one or more of said radial inward projections andsaid casing to maintain registry between said screws and said radialinward projections.

In testimony whereof I have signed my name to this specification, this16th day of July, 1918. i

JOHN S. TIMMONS

